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author | Bruno Haible <bruno@clisp.org> | 2017-09-08 10:02:47 +0200 |
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committer | Bruno Haible <bruno@clisp.org> | 2017-09-08 10:02:47 +0200 |
commit | 3ba4dbaefe671991083ff46a2714ff256adf75a1 (patch) | |
tree | abb123a27f29484f7a2484cfad73479c94eaa7e2 /lib/stddef.in.h | |
parent | 2890b02100598a5e2d1c8d2cc0104fac86e7ddf2 (diff) | |
download | gnulib-3ba4dbaefe671991083ff46a2714ff256adf75a1.tar.gz |
stddef: Avoid conflict with system-defined max_align_t.
The configure-determined HAVE_MAX_ALIGN_T may not always be accurate.
Reported by Werner Lemberg <wl@gnu.org> in
<https://lists.gnu.org/archive/html/bug-gnulib/2017-08/msg00185.html>.
* lib/stddef.in.h (rpl_max_align_t): Renamed from max_align_t.
(max_align_t): Define as a macro.
(GNULIB_defined_max_align_t): New macro. Guards against multiple
definitions of rpl_max_align_t in different copies of gnulib-generated
<stddef.h>.
Diffstat (limited to 'lib/stddef.in.h')
-rw-r--r-- | lib/stddef.in.h | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/lib/stddef.in.h b/lib/stddef.in.h index 2a11d2b71d..a79f5363df 100644 --- a/lib/stddef.in.h +++ b/lib/stddef.in.h @@ -85,24 +85,28 @@ a hack in case the configure-time test was done with g++ even though we are currently compiling with gcc. */ #if ! (@HAVE_MAX_ALIGN_T@ || defined _GCC_MAX_ALIGN_T) +# if !GNULIB_defined_max_align_t /* On the x86, the maximum storage alignment of double, long, etc. is 4, but GCC's C11 ABI for x86 says that max_align_t has an alignment of 8, and the C11 standard allows this. Work around this problem by using __alignof__ (which returns 8 for double) rather than _Alignof (which returns 4), and align each union member accordingly. */ -# ifdef __GNUC__ -# define _GL_STDDEF_ALIGNAS(type) \ - __attribute__ ((__aligned__ (__alignof__ (type)))) -# else -# define _GL_STDDEF_ALIGNAS(type) /* */ -# endif +# ifdef __GNUC__ +# define _GL_STDDEF_ALIGNAS(type) \ + __attribute__ ((__aligned__ (__alignof__ (type)))) +# else +# define _GL_STDDEF_ALIGNAS(type) /* */ +# endif typedef union { char *__p _GL_STDDEF_ALIGNAS (char *); double __d _GL_STDDEF_ALIGNAS (double); long double __ld _GL_STDDEF_ALIGNAS (long double); long int __i _GL_STDDEF_ALIGNAS (long int); -} max_align_t; +} rpl_max_align_t; +# define max_align_t rpl_max_align_t +# define GNULIB_defined_max_align_t 1 +# endif #endif # endif /* _@GUARD_PREFIX@_STDDEF_H */ |